New documentaries explore the star-crossed careers and delicate spirits of Wilt Chamberlain and Bill Walton, two of basketball’s greatest.Pity the poor 7-footer.That’s the message of two new documentary series about storied basketball players: “The Luckiest Guy in the World,” about Bill Walton (available in the “30 for 30” hub at ESPN Plus), and “Goliath,” about Wilt Chamberlain (premiering Friday at Paramount+ and Sunday on Showtime).Serious and thorough, “Luckiest Guy” and “Goliath” are positioned to draft on the success of an earlier basketball biography, ESPN’s popular Michael Jordan series, “The Last Dance.” But while they are also portraits of men with supreme physical gifts, they are less focused on their subjects’ on-court exploits and more determined to get inside the players’ heads. The sportswriter Jackie MacMullan delivers what could be a thesis statement for both in “Goliath”: “I’ve found that big men are much more sensitive than we realize.”Chamberlain, who died of heart failure in 1999, and Walton both have well-defined personas, which they participated in creating. Each series spends a lot of its time picking apart the received wisdom about its subject while also indulging, for the sake of dramatic impact and storytelling shorthand, the very stereotypes it wants to deconstruct: Chamberlain the unstoppable, insatiable giant; Walton the goofy, fragile flower child.The four-episode “Luckiest Guy” was directed by the accomplished documentarian Steve James, always to be remembered for “Hoop Dreams,” and was made with the full cooperation of Walton, 70, who revisits old haunts and sits down for an entertaining round table with Portland Trail Blazers teammates like Lionel Hollins and Dave Twardzik. It’s engagingly introspective and personal, in part because James pushes back against Walton’s incessant recitation of the title phrase. How can Walton call himself the luckiest guy in the world, James asks from behind the camera, when his career was utterly ravaged by injuries that eventually crippled him and drove him to consider suicide?That, broadly speaking, is the idea that haunts both documentaries. The conundrum of Walton’s and Chamberlain’s careers is that they were marked by success — college and professional championships, statistical domination (in Chamberlain’s case), reputations for unmatched athletic skills — and defined by disappointment. Neither won as often or as easily as he should have, in Walton’s case because of injury and in Chamberlain’s because of the dominance during the 1960s of the rival Boston Celtics and their center, Bill Russell, enshrined in sports mythology as the hard-working Everyman to Chamberlain’s sex-and-statistics-obsessed egotist.“Goliath,” directed by Rob Ford and Christopher Dillon, is a more workmanlike and conventional project than “Luckiest Guy.” But across three episodes it makes a persuasive case for Chamberlain as a generous, sensitive soul who was both blessed and constrained by his stature and his extraordinary all-around athletic ability.It does its sports-documentary duty, laying out Chamberlain’s triumphs and more frequent setbacks on the court. But it is more interested in the trails he blazed as a Black cultural figure and self-determining professional athlete, and it favors writers, pundits and scholars over basketball players in its interviews. (The scarcity of images from Chamberlain’s younger days in the 1940s and ’50s is compensated for with shadow-puppet scenes reminiscent of the work of Kara Walker.)Watching the series side by side, the differences between the two men are less interesting than the sense of commonality that emerges. Both were self-conscious stutterers who learned to endure, and perform under, the most intense scrutiny. Chamberlain may have been more flamboyant, but Walton, in “Luckiest Guy,” is just as conscious of his affect — there’s an ostentatiousness, and no small amount of ego, in the way he performs modesty. (James also challenges Walton’s lifelong, generally debunked claim to be only 6 feet 11 inches tall.)The veteran sports fan might see another commonality: As good as they are, neither “The Luckiest Guy in the World” nor “Goliath” is as exciting to watch as “The Last Dance.” This is a bit of a conundrum, because both Chamberlain and Walton are, quite arguably, more complex, interesting and moving figures than Michael Jordan. But Michael Jordan is a nearly unparalleled winner. And while winning isn’t the only thing, it is, for better or worse, the most compelling thing about the subject of a sports documentary. More